Field of the Invention
The present invention relates to a light source unit and a projector including this light source unit.
Description of the Related Art
In these days, data projectors are used on many occasions as an image projection system which projects a screen and a video image of a personal computer, as well as images based on image data which is stored on a memory card on to a screen. In these projectors, light emitted from a light source is collected to a micromirror display device made up of DMDs (Digital Micromirror Devices) or a liquid crystal panel to thereby project a color image on to a screen.
Conventionally, the mainstream of these data projectors has been those which utilize a high-intensity discharge lamp as a light source. In recent years, however, there have been made many developments on projectors which use, as a light source, light emitting diodes (LED), laser diodes, organic electroluminescent elements, and luminous light emitting or luminescent materials.
For example, Japanese Unexamined Patent Publication No. 2010-224493 discloses a projector which includes a light source which emits spotlight, a polygonal plate-shaped scanning member which reflects the spotlight and a color wheel. The scanning member reflects spotlight from the light source at a specified angle. The color wheel has three luminescent color filters which emit three colors of luminous light. These color filters are disposed end to end circumferentially in a divided fashion on the color wheel which is a rotatable circular disk. The scanning member has a plurality of mirrors which are arranged on a side surface thereof so as to correspond to the luminescent color filters, so that the luminescent color filters on the color wheel are sequentially scanned by the spotlight reflected by the mirrors. Then, the three colors of luminous light excited in the luminescent color filters are emitted in a time-sharing fashion as a plurality of colors of light source light.
In the projector disclosed by Japanese Unexamined Patent Publication No. 2010-224493, however, the resulting red light, green light and blue light are the light obtained by exciting luminescent materials of colors which correspond to the color filters provided on the color wheel by the spotlight which is emitted from the single semiconductor laser light source and which has a wavelength in a range of ultraviolet wavelengths. The luminous light is emitted from an opposite side of the color wheel to the surface that the spotlight enters and then enters the integrator for use as the light source of the projector. However, light excited by a luminescent material is sometimes emitted in various directions, and therefore, the other luminous light than the luminous light that enters the integrator cannot be used as the light source light. In addition, as in Japanese Unexamined Patent Publication No. 2010-224493, in the event that a color to be obtained as light source light corresponds to a certain segment of the segments of color filters, this particular segment cannot be used to emit another color of light. Because of this, in the event that the number of colors to be used to form an image is changed depending on a projection mode, all the segments cannot be used, resulting in a reduction in luminance of a projected image.